Cylinder liners
New and reconditioned liners, O-ring kits, seat and landing-ring seals, and the cylinder-unit parts that come off with them. For a reconditioned liner, ask for the inspection report stating what was measured and repaired.
Main engine RFQ route
Piston, Liner
Piston, Liner
& Cylinder Parts Supplier
Main engine overhaul spare parts supply built from clear vessel and engine evidence.
Engine identityMaker, model, serial and part-book logic
Overhaul contextPistons, liners, rings, bearings and gaskets
Route reviewOEM and verified alternative direction
Schedule awarePort, ETA and urgency kept in the brief
Main engine supplier
High-value engine RFQs need a clean technical brief before supply route review starts.
Vessel Core supplies main engine piston rings, pistons, cylinder liners, cylinder components, injectors, bearings, gaskets and related overhaul items.
The strongest requests include engine maker/model, serial number, part-book page, drawing, photos, old offer or invoice reference, quantity and vessel timing.
Supply scope
Main engine components and related overhaul items.
Focused around the component clusters that require careful cross-checking before quote work.
Pistons
Piston crowns and skirts, complete piston assemblies, and on slow-speed engines the piston rod and crosshead parts that a trunk-piston part book does not list separately.
Piston rings
Compression ring sets — and on trunk-piston engines oil scraper rings too — matched to the engine designation and build, the liner oversize and the measured condition of the bore. On a crosshead engine with cylinder lubricators, the cylinder oil feed rate calculator puts the oil used beside the power and the hours as a feed rate in g/kWh.
Cylinder parts
Cylinder covers, complete exhaust valves, valve cages, spindles and seats, guide bushes, cover studs, nuts and sealing rings.
Injectors
Complete injectors — listed as fuel valves in two-stroke part books — and nozzles, plunger-and-barrel assemblies and injection pump parts, high-pressure fuel pipes, delivery and non-return valves. On many medium-speed engines this hardware comes from L'Orange rather than the engine builder, so the marking on the injector or pump body belongs in the request beside the engine builder's number.
Bearings and gaskets
Main and crankpin bearing shells, crosshead bearing shells on slow-speed engines, crankshaft thrust bearing half-rings, and overhaul gasket and sealing kits. See also seals, gaskets and bearings.
Parts list
Typical request items for the piston-cylinder unit
Running spares, planned-maintenance kits and individual items critical to the vessel's schedule — grouped by engine system so the request is easier to put together and easier to check against the part book.
- Cylinder liners and O-ring kits
- Piston crowns and skirts, complete pistons
- Piston rods and crosshead parts
- Compression and oil scraper ring sets
- Cylinder covers and cover gaskets
- Complete exhaust valves, valve cages, spindles and seats
- Guide bushes and valve stem seals
- Studs, nuts and fasteners for the cylinder unit
- Complete injectors and nozzles
- High-pressure fuel pumps, plunger-and-barrel assemblies and high-pressure fuel pipes
- Main, crankpin and crosshead bearing shells, thrust-bearing half-rings
- Connecting-rod bolts and small-end bushes
- Piston-rod scraper rings and stuffing-box seals
- Cylinder lubricator parts
- Gasket and seal repair kits
In the field
What the cylinder covers and valve gear look like on an open engine.
The first photograph is licensed and representative only, not a Vessel Core installed reference or completed job — photo: Michael Krahe, Wikimedia Commons, CC BY-SA 4.0. The second and third are Vessel Core's own, taken aboard a vessel during a yard visit in July 2026 and published with the owner's permission. No manufacturer is identified in any of the three, and none of this is a claim that Vessel Core supplied or worked on the equipment shown.
What to send
Give enough evidence to avoid wrong engine route assumptions.
Even one clear part-book page, old quote line, photo of a marking, or packing list reference can reduce ambiguity before the supply route is reviewed.
- Maker, full engine designation and build
- Engine serial number and the number of cylinders
- Part-book page, drawing or position number
- Part number or the part-book designation
- Previous order reference, invoice wording or packing-list wording
- Photograph of the marking on the piston, the liner or the engine nameplate
- Quantity per line
- Nature of the work: planned maintenance, condition-based repair or unit replacement
- Owner and class approval requirements — whether type approval and a class certificate are needed
- Port of call and ETA
Missing a part number is not a reason to hold the request. Send the engine nameplate, a part-book page, a drawing, a previous order reference or the wording from an invoice — see the RFQ evidence guide, the evidence checklist and RFQ without a part number. No line is confirmed on an engine series name alone.
Engine identity
- Maker
- Model
- Serial number
- Build or spec note
Part evidence
- Part-book page
- Drawing
- Part number
- Component photo
Commercial reference
- Old offer
- Invoice wording
- Packing list wording
- Quantity
Vessel timing
- Vessel / IMO
- Urgency
- Port
- ETA
Why Vessel Core
More than one supply route is weighed on every cylinder-unit RFQ.
OEM routes and verified alternatives are assessed on the part evidence, the owner's and class approval requirements, the documentation available and the vessel's schedule. A route is confirmed only after the RFQ is reviewed.
Technical matching before commercial
The part designation, the part-book page and the engine serial number are checked before any route is weighed. Neighbouring builds in one family are told apart on the part-book page, not by assumption.
OEM or verified alternative
An OEM-route review can be requested where class requirements apply or a class certificate is needed. Verified alternatives are reviewed for running spares. The comparison sits on OEM and alternative parts, and the supply route advisor takes one line through the same factors.
Completeness of the overhaul kit
With pistons, liners and covers it is worth putting the rings, O-rings, gaskets, studs and fasteners into the same request — so an opened cylinder is not held up by a small item once the work has started. A loose O-ring without a kit reference can be named from its inside diameter and cord section in the O-ring size finder.
Slow-speed and medium-speed differ
Crosshead and trunk-piston part books are built differently: where a trunk-piston engine lists a single piston, a crosshead engine lists crown, skirt, piston rod and crosshead parts separately. Both are accepted, and the build is confirmed before matching — see the MAN and Wärtsilä sourcing guide.
Port of call and the work schedule
Route, handover and freight are assessed against the RFQ evidence: port of call, ETA, documentation requirements. Lead time is confirmed only in the quotation for the specific line.
An EU legal entity
Vessel Core OÜ is registered in Estonia, registry code 17028043, VAT EE102773714 — public details, a named RFQ contact and a documented way for a buyer to verify the company.
Cylinder-unit FAQ
Piston, liner and cylinder parts — common questions
What evidence does a cylinder-unit RFQ need?
Maker and full engine designation, serial number, a part-book page or drawing, the part number, a photograph of the marking on the piston or liner, quantity, port of call and ETA. That is enough to start matching without assuming the engine build.
Can a request be sent without a part number?
Yes. Send a photograph of the engine nameplate, a part-book page, a drawing, a previous order reference or the wording from an invoice or packing list. No line is confirmed on an engine series name alone.
Are OEM and verified alternative routes both reviewed?
Yes, per RFQ, against the evidence, the owner's and class approval requirements and the vessel schedule. Where class requirements apply or a class certificate is needed, ask for an OEM-route review. Lead time is confirmed only in the quotation.
Which parts count as cylinder-unit parts?
Liners with their O-ring kits, complete pistons, crowns and skirts, piston rod and crosshead parts on slow-speed engines, ring sets, cylinder covers with exhaust valves, spindles, seats and fasteners, and main and crankpin bearing shells with the gaskets and seals that go back with them.
Related routes
Connect main engine RFQs to the wider supply route path.
Send main engine RFQ
Have piston, liner or cylinder parts to source?
Send engine data, part-book evidence, quantity, old commercial reference if available, and port/ETA. We will route the request for technical cross-checking.
